Abstract: BACKGROUND: At present, domestic and foreign studies mainly focus on the comparison of different operation methods for intertrochanteric fracture of femur and the risk of failure in proximal femoral nail antirotation operation. There are few studies on the prognosis of hip function of affected limb after proximal femoral nail antirotation.   
OBJECTIVE: To analyze the influencing factors of poor hip function recovery in elderly patients with intertrochanteric fracture after proximal femoral nail antirotation surgery, and to construct a score system for predicting hip function after surgery and explore its value. 
METHODS: A total of 150 patients with intertrochanteric fracture of femur who received proximal femoral nail antirotation surgery in the Affiliated Hospital of Xuzhou Medical University from June 2021 to June 2023 were selected and divided into groups according to the Harris hip function score during postoperative follow-up. A score ≥80 was considered as the good group, and a score < 80 was considered as the poor group. Univariate and binary regression analyses were used to explore the risk factors leading to postoperative hip dysfunction. A score scale was established according to the risk factors. The value of this scoring system in predicting hip function after proximal femoral nail antirotation was investigated by using receiver operating characteristic curve. 
RESULTS AND CONCLUSION: (1) Among the 150 patients, according to the Harris score standard of the affected hip joint at 1 year follow-up, there were 52 cases in the group with poor functional recovery and 98 cases in the group with excellent functional recovery, with an unsatisfactory rate of 34.7%. (2) The results of univariate comparison between the two groups showed that there were significant differences in age, bone mineral density, number of preoperative underlying complications, type of lateral wall, position of spiral blade, quality of reduction and time of first exercise after surgery between the poor group and the good group (P < 0.05). (3) The results of binary Logistic regression analysis showed: Age ≥75 years old (OR=2.834), osteoporosis (OR=3.002), number of preoperative basic complications > 2 (OR=4.024), lateral wall rupture (OR=2.999), position difference of spiral blade (OR=4.025), and time to exercise for the first time after surgery > 4 weeks (OR=3.153) were independent risk factors for hip dysfunction after proximal femoral nail antirotation for the intertrochanteric fractures (P < 0.05); poor reduction quality (OR=1.026) was not an independent risk factor (P > 0.05). (4) Based on the results of binary regression analysis, a score system for predicting good hip function after surgery was established. Receiver operating characteristic curve analysis showed that the threshold for predicting poor hip function after surgery was 4.5 points; the area under the curve was 0.797; the sensitivity was 83.7% and the specificity was 65.4%. (5) These results suggested that age ≥75 years old, osteoporosis, number of preoperative basic comorbidities > 2, lateral wall rupture, poor position of spiral blade, and first time out of bed exercise > 4 weeks after intertrochanteric fracture were risk factors for hip dysfunction after proximal femoral nail antirotation. The establishment of a score prediction system can provide reference value for early clinical identification of high-risk patients with postoperative hip dysfunction, and is conducive to guiding early clinical intervention, adopting more personalized treatment and rehabilitation programs, and promoting the recovery of hip function in patients after surgery.

Key words: intertrochanteric fracture, proximal femoral nail antirotation, follow-up, hip function, osteoporosis, risk factor, orthopedic implant